There are two main forms of lasers of this type, namely CO.sub.2 mixing lasers and supersonic CO lasers.
Common examples of CO.sub.2 mixing lasers are described in an article entitled "High-Power CO.sub.2 Electric Discharge Mixing Laser" by Clyde O. Brown and published in Appl. Phys. Lett. Vol. 17 dated November 1970 at pages 388-391, and also in a report entitled "A 30-kW CO.sub.2 Mixing Laser" by Ross C. McLeary, Russell E. Whitcher and Peter J. Beckwith and published in a Materials Research Laboratories' report MRL-R-751 dated July 1979.
It is known with such CO.sub.2 mixing lasers to, in the excitation stage, continuously excite a gas having a relatively long excitation life, and to subsequently continuously feed the excited gas into a mixing zone in the power extraction stage where it is mixed with CO.sub.2, or CO.sub.2 and He, and transfers its excitation to the CO.sub.2 which has a relatively shorter excitation life. The gas mixture subsequently passes to the resonator to produce a laser beam.
A known form of supersonic CO laser is disclosed in an article entitled "Performance of a Large, CW, Pre-excited CO Supersonic Laser" by John W. Daiber and Herbert M. Thompson and published in IEEE J. Quantum Electron, Vol. QE-13, dated January 1977 at pages 10 to 17. It is known with such supersonic CO lasers to continuously excite CO in the excitation stage. CO, which has a relatively long excitation life, is continuously fed under supersonic conditions to the resonator of a cooled power extraction stage to produce a laser beam.